Buttonhole sewing machine



May 12, 1936'. .M. J. KENNY ,040,260-

BUTTONHLE SEWING MACHINE Original FiledOct. 8, 1931 '2 Sheets-Sheet 1lnvenToT.

Michoe \J. Kenny AT Tys.

12, 1936. M. J. KENNY 2,040,260

v BUTTONHOLE SEWING MACHINE Original Filed Oct. 8, 1931 2 Sheets-sheet 2Fig.2.

\nvenTor.

Michael a). Kenny ATTys.

Patented May 12, 1936 UNITED STATES PATENT OFFICE poration of Maine 101-to Hole Machine Company, Boston, Mass, a cor- The Reece ButtonApplication October 8, 1931, Serial No. 567,560 Renewed November 9, 19334 Claims.

This invention relates to buttonhole sewing machines.

In buttonhole sewing machines the work in which the buttonhole is to besewed is held in 5 work-holding means which comprises two clamp platesor mat members, one each side of the buttonhole slit, on which the workis supported, and two work clamps, one each side of the buttonhole slit,which serve to clamp the work against the mat members, and usually theedges of the clamp members and mat members are in vertical alignment.

In sewing the buttonhole the needle makes its thrusts alternately in theline of the buttonhole slit and through the goods at a distance backfrom the line of said slit. For convenience the needle thrusts throughthe line of the buttonhole slit will be referred to as the slit thrustsand those through the goods back from the slit as depth" thrusts.

stitches will appear on the back face of ghe'goods as short lengths ofthreads ex mding'from the" buttonhole slit to the H nts where, theneedle made the depth thrusts?" Where the depth thrusts arerelativelymeld's e to the buttonhole slit so that the lengths'"of thestitches appearing on the back face of the fabric are relatively short,the buttonhole is commonly referred to as one with a narrow bight, theterm "bight referring to it the length of the stitches as they appear onthe back face of the fabric. On the other hand, when the depth thrustsof the needle are through the work at a considerable distance back fromthe buttonhole slit so that the stitches as they appear on the back faceof the fabric are of generous length the buttonhole is commonly referredto as sewed with a wide bight.

Where a buttonhole is sewed with a narrow bight, on buttonhole sewingmachines as now manufactured it frequently happens that the needle holeswhich are made in the work during the formation of the depth stitcheswill be visible after the stitching is completed thereby producing onthe back face of the fabric, and sometimes on the front face also,- amarking which represents the line of holes made by the depth thrusts ofthe needle. One reason for the production of this marking is because theworkholding means is usually so adjustedthat the inner aligned edges ofthe work clamps and mat members are situated just, outside the linewhere the needle makes its depth thrusts so that each depth thrust ofthe needle comes close to the aligned edges of the work clamps and matmembers.

When the buttonhole is completed the In sewing a buttonhole with anarrow bight these aligned edges are relatively close to the buttonholeslit and hence a correspondingly narrow portion or strip of the workimmediately circumjacent the line of the buttonhole slit will beprojecting beyond the work clamp and mat and the work is firmly heldalong the line just outside of the line of the depth thrusts and hencerelatlvely close to the line of the buttonhole slit.

The needle of a buttonhole sewing machine is necessarily of greaterdiameter than the thread used in sewing the buttonhole and hence thehole which the needle makes in the work during,

the depth thrust will be larger than the thread. 7

Where a buttonhole with a narrow bight is bein sewed in fabrics havingcertain Characteristics the hole which the needle makes during its depththrust will remain visible after the thread has been drawn through. Onereason for this is because when the needle makes its depth thrust itcrowds the threads of the fabric apart and where only a very narrowportion of the fabric is extending beyond the portion which is firmlyclamped in the work holder, as is the case when a buttonhole with anarrow bight is being sewed, the displacement of the threads in saidnarrow portion occasioned by the depth thrust of the needle stretchesthe narrow edge of the fabric projecting beyond the portion which isclamped between the work clamp and mat beyond its ability to recover andproduces a permanent rearrangement of the threads of the fabric whichleaves a visible needle hole in the fabric. The visibility of the needlehole is augment ed by the tension which is applied to the thread informing the depth stitch. When each depth stitch is tightened thetension on the thread applies a pulling strain to the work which tendsto maintain the needlehole and thereby increase its permanentvisibility.

This permanent marking of the fabric constitutes a disfigurement whichit is desirable to avoid and it is one of the objects of my presentinventionto provide a novel buttonhole machine construction which willpermit of the sewing of a buttonhole with a narrow bight withoutproducing the permanent markings along the edge of the buttonhole formedby the depth thrusts of the needle.

In accomplishing the above object, the mats and the work clamps are soconstructed that the edge of the mat is situated further from the lineof the buttonhole slit than the edge of the work clamp, in other words,the work clamps and mats have such a relative arrangement that the innerwork-whichis.clampe ilgtween the mats and the work clamps. and thisgerfious 'width of work In stitching a buttonhole the alternate thrustsof the needle 6 are in the line of. the slit !4 and the other thrustsare through the fabric at points l5 situated at a distance back from theslit l4, and as stated above, the needle thrusts through the slit It mayconveniently be referred to as slit thrusts while those through thefabric at points [5 may be referred to as depth thrusts. The full lineposition of the needle in Fig. 3 is the position the needle occupies inmaking the slit thrust and the dotted line that which it occupies inmaking the depth thrust.

which projects beyond the mat is supported by Ti-ie-worln clamps I areusually o adjusted the relatively wide throat plate during the sewingoperation. Such generous width of work provides sufiicient elasticity inthe portion of the fabric through which the depth thrusts are made sothat when the needle is withdrawn from the work the needle hole will beclosed up. With the needle holes all closed up the line of marking whichis referred to above and which is caused by the needle holes will beobviated and a buttonhole with a narrow bight can be made withoutproducing this undesirable marking on the goods.

In order to give an understanding of the invention I have illustrated inthe drawings a selected embodiment thereof which will now be describedafter which the novel features will be pointed out in the appendedclaims.

Fig. 1 is a side view of a portion of a buttonhole sewing machineembodying my invention;

Fig. 2 is a top plan view of the work-holding means, said figure alsoshowing the throat plate carried by the turret;

Fig. 3 is a section on the line 33, Fig. 2 but s he throat plate andneedle in the posim ring the sewing of the buttonhole' Fig. 4 is a viewof a butfi'n'hh I The principal elements of the s t'vn chine hereinillustrated are similar to those iisually found in buttonhole sewingmachines. M

The work-holding means comprises pivoted work clamps I, one located eachside of the line of buttonhole slit, which clamp the work 2 against themat portions 3 of clamp plates 4 that are carried by the bed 5 of thesewing machine frame. The mat portions 3, one of which is situated eachside of the buttonhole slit, are usually provided with a roughenedwork-receiving surface.

The stitch-forming mechanism includes the needle 6 carried by avertically-reciprocating needle bar i and operating above the work andthe usual under thread mechanism which is mounted on a rotary turret 8situated beneath the work. The turret 8 also carries a throat plate 9which is provided with a sewing opening I!) in which the needle 6operates as it makes its penetrating thrust.

It will be understood, of course, that the stitchforming mechanism andwork-holding means are capable of moving relative to each other toprovide for the feeding movement necessary to form the stitches alongthe edges of the buttonhole. In the machine herein shown thestitch-forming mechanism is carried by a frame H which is mounted on thebed 5 and which may conveniently be referred to as the stitch frame.Said stitch frame and bed have a relative movement to provide for thenecessary feeding movement above referred to.

The machine herein shown is also provided with the usual buttonholecutter comprising two cutting elements l2 and I3 which co-operate to cutthe buttonhole slit l4.

that the edges i5 thereof lie closely'a facent to the line in which thedepth thrusts of the needle are made.

In accordance with the present invention I propose to make the matmembers 3 so that their inner edges H are more widely spaced from eachother and each is at a greater distance from the line of the buttonholeslit l4 than the inner edges is of the work clamps. In other words,instead of making the mats with the inner edges II in alignment with theedges N3 of the work clamp or closely adjacent the line in which thedepth thrusts of the needle are made, said edges 5? of the mats are cutback a substantial distance from said line of depth thrusts as shownbest in Fig. 3. As a result of this construction, the inner edges E5 ofthe work clamps overhang the edges ll of the mat and when the workclamps are in operative work-clamping position the portion of the work 2which is firmly clamped between the work clamps and the mat will be theportion outside of the edges 1'! of the mats, the portion of the workbetween the edges ll of the mat and the line of the buttonhole slitbeing unclamped. Hence with this construction there is a zone of fabricof substantial width immediately circumjacent the buttonhole slit whichis not subjected to the clamping action of the work hp lQer and themats, which zone is wider than the zon mcluded between the buttonholeslit and the line of depth thrusts of the needle or, in other words, thezone which .is covered by the stitches E8 of the buttonhole.

The throat plate 9 is made with a work-supporting surface IQ of generouswidth. In fact, said. work supporting surface I9 is wider than the spacebetween the edges 16 of the work clamps during the sewing operation withthe result that the throat plate 9 underlies the inner edges of the workclamps. Preferably this throat plate will be made of a size tosubstantially fill the space between the edges I! of the mat portions.

While the throat plate underlies the work as shown in Fig. 3 yet thework is not clamped between the throat plate and the work clamps in thesame way in which it is clamped between the work clamps and the mats 3because during the sewing operation the throat plate moves underneaththe work in the direction of the length of the buttonhole, as will beunderstood by those skilled in the art.

With this construction when the needle makes its depth thrust as shownby dotted lines in Fig. 3 such thrust is made at a point somewhatseparated from the portion of the fabric which is firmly clamped betweenthe work clamps and the mat members 3 and hence as the depth thrust ismade the threads on all sides of the needle will be displaced slightlyas the needle passes through the goods. When the needle is withdrawnfrom the goods the elasticity ofthe fabric in the relatively wide zoneof unclamped fabric will cause the displaced threads to again assumetheir normal position with the result that the needle hole will besubstantially closed up and will not be visible. Furthermore, where theabove-described construction is employed the amount of unclamped workbetween the line where the clamping action takes place, to wit, the lineof the inner edge I! of the lower work-clamping member 3, and the linewhere the depth thrusts l5 are made, will allow sufficient give orstretch when the pulling strain is applied to the thread to tighten thedepth stitch so that the tension on the thread will not unduly enlargethe needle holes as frequently happens when the work clamps areconstructed so that the work is clamped close to the line of depththrusts.

The throat plate supports the work during the penetrating thrust and theoverhanging portion of the work clamps prevents the work at thebuttonhole slit from being lifted up when the needle is retracted. Therewill, therefore, be no undue stretching of the work while the needle ismaking its penetrating thrust which will tend to produce a permanentneedle marking on the goods. The advancing or forward edge 20 of thethroat plate is square and is situated at right angles to the directionof movement of the throat plate during the sewing operation. This is anadvantage as it not only gives a larger work-supporting surface to thethroat plate but provides a construction in which the movement of thethroat plate against the under side of the work during the sewingoperation is less likely to distort the unclamped portion of the goodscircumjacent the buttonhole slit.

With this invention it is possible to sew a buttonhole with a verynarrow bight, that is, to sew a buttonhole in which the depth thrusts ofthe needle are relatively close to'the buttonhole slit, without leavingany needle markings such as oc cur frequently in buttonholes sewed witha narrow bight in which the inner edges of the mat are situated close tothe line of the depth thrusts of the needle.

I claim:

1. A buttonhole sewing machine comprising a needle operating above thework and adapted to make slit thrusts and depth thrusts through thework, work-holding means comprising means to clamp the work each side ofthe buttonhole slit while leaving an unclamped zone immediatelycircumjacent the buttonhole slit which is somewhat wider than the zonebounded by the depth thrusts of the needle and a throat plate situatedbeneath the work and supporting the unclamped portion thereofimmediately circumjacent the buttonhole slit, which throat plate movesrelative to the work as the sewing proceeds, the advancing end of thethroat plate being situated substantially at right angles to thedirection of movement.

2. A buttonhole sewing machine having stitchforming mechanism includinga needle operating above the work and adapted to make alternate slit anddepth thrusts through the work, workholding means comprisingwork-supporting mats, one each side of the buttonhole slit, on which thework rests and work clamps, one for each mat, for clamping the workagainst the mats, the inner edges of the mats being spaced further fromthe line of the buttonhole slit than the inner edges of the work clamps,whereby the work clamps overhang the inner edges of the mats, and athroat plate which moves beneath the work as the sewing proceeds, saidthroat plate having a wide work-supporting surface to underlie theoverhanging portions of the work clamps and a square advancing end.

3. A buttonhole sewing machine having workholding means includingwork-supporting mat members, one each side of the buttonhole slit, andwork clamps for clamping the work against said mat members, the inneredges of the mat members being more widely spaced from the line of thebuttonhole slit than the inner edges of the c work clamps, whereby saidwork clamps overhang the inner edges of the mats, stitch-formingmechanism including a needle operating to make thrusts alternately inthe line of the slit of the buttonhole and through the fabric at a pointadjacent the edges of the work clamps but spaced from the edges of themats, and a throat plate beneath the work having a relatively wideworksupporting surface which underlies the overhanging portion of thework clamps and also having a square advancing end. i

4. A buttonhole sewing machine having stitchforming mechanism includinga needle, a throat plate beneath the work, said throat plate and workhaving a relative movement as the sewing proceeds, and the advancingside of the throat plate being straightand extending at right angles tothe direction of relative movement, said throat plate having a sewingopening to receive the needle, work-supporting means on which the workrests, and clamping means to clamp the work against the supportingmeans, said clamping means overlying the throat plate.

MICHAEL J. KENNY.

